Self locking receptacle and plug for electrical wiring devices



Nov. 27, 1962 H. HUBBELL ETAL 3,066,276

SELF LOCKING RECEPTACLE AND PLUG FOR ELECTRICAL WIRING DEVICES Filed May 25, 1959 2 Sheets-Sheet 1 72 INVENTORS BW Z 1 WAM WM A fkfis fs I N 1962. H. HUBBELL ETAL I 76 SELF LOCKING RECEPTACLE AND PLUG FOR ELECTRICAL WIRING DEVICES Filed May 25, 1959 2 Sheets-Sheet 2 INVENTORS BY 4 0.71m?

United States; Patent Gfifice 3,066,276 Patented Nov. 27, 1962 SELF LOCKING RECEPTACLE AND PLUG FOR ELECTRICAL WIRING DEVICES Harvey Hubbell and Benjamin C. Webster, Southport,

Conn., assignors to Harvey Hubbell, Incorporated, Bridgeport, Conn., a corporation of Connecticut Filed May 25, 1959, Ser. No. 815,502

4 Claims. (Cl. 339189) This invention relates to electrical wiring devices of the type for making detachable electrical connections, and particularly to those having interlocking means which prevent the accidental separation of the connecting parts during use thereof.

Interlocking electrical connectors are known in the art, and usually comprise two connecting parts which carry electrical contacts that engage each other on relative longitudinal movement of the parts toward each other to cause electrical connection, the electrical contacts on one of the parts being designed to interlock with a portion of the other part thereafter on the occurrence of relative rotation of the parts. An excellent example of a highly commercially successful electrical connector of the foregoing type is set forth in Patent No. 1,771,729 of Harvey Hubbell, Jr., granted July 29, 1930, entitled Interlocking Plug and Cap. Whereas this type of electrical connector is entirely satisfactory for its intended purpose, it does require two distinct movements on the part of the user to effect interlocked electrical connection, viz., first, longitudinal pushing of the connector parts toward each other, and, a second turning of the parts relative to each other.

It is an object of this invention to provide an improved interlocking electrical connector wherein interlocked connection of connector parts can be effected by the single motion of pushing the connector parts longitudinally toward each other.

The object of this invention is achieved in one form by incorporating in known interlocking electrical connectors resilient means which automatically acts on one or more of the electrical contacts of one of the connector parts after the parts are moved longitudinally toward each other to make electrical connection, to cause the parts to rotate relative to each other to effect interlocking.

The above and other objects of our invention and further detailsof that which we believe to be novel and our invention will be clear from the following description and claims taken with the accompanying drawings,

wherein: FIG. 1 is a side elevational view of the two main parts of an interlocking electrical connector which incorporates our invention;

FIG. 2 is a front elevational view on an enlarged scale of one modification of one of the parts; FIG. 3 is a fragmentary side elevational view of the connector part shown in FIG. 2, with portions broken away and shown in section for the sake of clarity;

.FIG. 4 is a bottom plan view of the connector part shown in FIG. 2 after the base plate thereof has been removed;

FIG. 5 is a sectional view taken substantially on line tion may be readily incorporated into other electrical con-,

nectors, such as electrical connector and cap assemblies and the like.

In FIG. 1 there is generally illustrated anelectrical connector which incorporates the instant invention, in the form of an electrical plug 10 and an electrical receptacle 12. The plug 10 comprises a disk-like dielectric body member 14 which supportsa plurality of current-carrying electrical terminal and contact units 16 on one side there of. Each of the units 16 comprises an electrical terminal portion (not shown) which is rigidly secured to the member 14 on one side thereof, and a male electrical contact finger 17 which projects away from the member 14. The contact fingers 17 are spaced circumferentially, and on the same lateral side of each of the contact fingers 17 there is formed a laterally projecting portion 18 which constitutes a part of the connector interlocking means, the detailed construction and operation of which will be set forth subsequently. On the other side of the member 14, a cable clamp 20 is mounted and functions to secure the electrical cable 22 to the member 14. The clamp 20 may be of any known design, and the member 14 is pro vided with a central opening (not shown) which allows an end of the cable 22 to pass therethrough to the side thereof on which the terminal portions of the'units 16 are disposed, where the cable leads (not shown) may be connected to said terminal portions in any suitable known manner. The other end of cable 22 (not shown) may be wired to any suitable electrical component.

The receptacle 12 generally comprises a so cketed di: electric body member 24 which includes a raised circular slotted front wall 25 on the front thereof and adetach ably mounted dielectric base plate 26 on the rear thereof. The member 24 and base plate 26 may be conveniently detachably secured to each other by the screws 28 which are received in appropriate cooperating openings formed in the member '24 and the base plate 26, and threadedly anchored in threaded openings formed in the mounting ear brackets 30 that are disposed on the front of the mem ber 24 on thesides of raised Wall 25. Brackets 30 are adapted to receive mounting screws 32 in openings formed therein for the purpose of mounting the entire receptacle 12 on any convenient supporting wall. I I

As illustrated, the plug 10 and receptacle 12 are de signed to make interlocked electrical connection for a wired'device having four-wire cable, and therefore, there are four electrical terminaland contact units 16 formed on the-plug 10 and ,four cooperating electrical contact making and interlocking means, which will be described subsequently, formed on thereceptacle 12, It will be understood by those skilled in the art that wired devices with cables having numbers of wire s'other thanfour, such as two or three wires, may have the instant invention incorporated therein. i I

Receptacle 12 includes means for making electricalcom tact with the plug and means for interlocking the plug and receptacle when they are connected. The electrical con tact making me'anson'the' receptacle 12 comprises four electrical terminal and cont'actunits 34 which are dis-. posed in an appropriate spaced manner in the receptacle body member 24, and each of which comprises a spring clip fernale'contact portio'n'36 and a terminal'portion 38. As can best beseen in FIG. 2, the receptacle front wall 25 has four arcuate slots 40 formed therein which are adapted to receive the plug contact fingers 17 when the connector parts are connected. f One of the slots 4.0has. aradially extending portion 42 which may cooperate witha radially projecting portion 44 formed on one of the plug contact fingers 17 (see (FIG. 1) to aid in properly aligning the plug and receptacle during their connection. The slots 40 are disposed to communicate with four socket-like cavities 46 formed in the receptacle body member '24 by Walls thereof and'which house the units 34. The cavities 46 each' contain laterally oppositely extending portions 48 and'50 and aradially outwardly extending portion 52;'in the context of the illustrated form of the inventionfth'e term laterally means circumferentially. The entire cavities46 open on the rear side of the body member 24 and are adapted to be closed on that side by base plate 26 when the receptacle 12 is fully assembled. As can best 'be seen in FIGQZ, the cavity portions 48, when the receptacle is viewed from itsfront, are covered by portions of front "wall 25,whereas cavity portions 50 are "not covered by front wall 25, and therefore are directly accessible through slots 40. The slots 40, cavities 46 and units 34 are structurally and dispositionally related so that the open ends of the U-shaped spring clip female contact portions 36 face the slots 40, and therefore, are disposed to make electrical contact with the plug contact fingers 17 when the plug is moved longitudinally toward thereceptaclel2 and the fingers 17 are appropriately and sufiiciently inserted into the receptacle slots '40, It will be'obse'rved that the slots 40 are wide enough (their circumferential dimension) to accommodate the plug contact fingers 17 and their lateral projecting portions when engagement is made between the plug contact fingers 17 and the receptacle female contact por tions 36, the legs of the female contact portions 36, which are inherently exible, flex radially, and the cavity portions 52 provide room for such flexure. v It will, therefore, be apparent that with the electrical connector structure'described thus. far, in order to effect electricalconnection, the plug 10 and'receptacle 12 are riioved longitudinally toward each other, and that this results in the plug contact fingers 17 being inserted and received between the flexible. legs of the female contact portions 36 of the units In order to effect interlocking of the plug and receptacle in known prior art interlocked electrical connector constructions, such as the. referred to'patent to Harvey Hubbell, Jr., it is necessary to rotate (turn) one of the connector parts, e.g theplug, relative to the other connector part, e.g., the receptacle, after the connector parts have been moved longitudinally (pushed together) toward each other as far as they can go and electrical connection of the connector parts has been made. For convenience inunderstanding the operation of known prior artdevices, reference may be had to FIG'SJ'Z' and '5 Relative rotation of the connector parts results in the plug contact fingers 17 and their projecting portions ls 'being rotated clockwise relative to the cavities' li6 inthe receptacle body member 24, but/electricaI contactbet'ween the connector parts is continuously maintainedf Such relative rotation results in the projecting puritans 18 beingrnoved laterally to positions whereiat ey"transposed under the portions of thereceptacle front wall 25 which overlie the portions 48 of receptacle cavities 4:6. When the connector pa r tsare in this position, longitudinal movement of the connector parts away, from eac'h 'other '(intentional or unintentional pulling apart) will not result in disconnection of the parts, because the projecting portions 18 make interference contaetwith the inner surfaces 5.3 of the front wall portions thatoverlie' 'the cavity portions 48. It will be understood that reference to FIGS. 2 and and the above explanation with'relation thereto is for the. purpose of convenieneein' understanding theoperation of known priorartdeyicesand. not intendedto. be a description of the operation; of the illustrated improved interlocking electrical connectors contemplated by the instant invention.

The structure and operation described thus far isthe pri rQa'r-t setting for theinstantinvention, which is animn sv mstitssl ach nq a mar i t t qs ns l tr connectors. The instant invention contemplates the addition and incorporation of novel structure into the described known prior art connectors which eliminates the necessity of the users turning the connector parts relative to each other to effect interlocked connection thereof after the connector parts have been pushed together. This novel structure comprises means for automatically causing relative rotation of the connector parts after the connector parts have been moved sufficiently longitudinally toward each other. In both modifications of the illustrated form of the invention, this novel structure is incorporated into the receptacle and comprises resilient camming means which is associated with some of the receptacle female contact portions 36 and which cooperates with some of the plug contact fingers 17 to cause relative rotation of the connector parts at the proper time during connection thereof. This is the preferred form of both modifications of the invention. However, it will be understood by those skilled in the art that novel structure for causing automatically such rotation could be readily incorporated into the plug, as by being associated with the plug contact fingers 17, without departing from the spirit of the invention.

As illustrated in the preferred form of the modification set forth in FIGS. 2' to 8, the resilient camming means comprises a pair of bow-shaped leaf springs 54 which are illustrated as being associated with two alternate units 34. Fewer or more leaf springs 54 may be employed depending on their strength, the illustrated arrangement including two leaf springs having been found successful in practice. As illustrated, each leaf spring 54 is structurally incorporated into a different unit 34 by having one end 56 bent and rigidly attached to a fiat base 58 of a unit 34 and the base of a female contact portion 36, as by the rivet 60, as can best be seen in FIG. 3. The bowed central portion 62 of the leaf spring 54 normally is disposed to extend near adjacent edges of the legs of its associated female contact portion 36. The free ends 64 of the leaf springs 54 respectively contact radial wall portions 66 which in part define the portions 50 of the receptacle cavities 46, and the wall portions 66' function as backing walls for the leaf springs.

The leaf springs 54 function to cause automatic rotation of the plug. contact fingers 17, and the plug 10, after said fingers are inserted into the slots 40 and cavities 46 a certain amount. This can be best understood by refer ence to FIGS. 6, 7 and 8, wherein this operation is set forth. In FIG. 6, the condition of the relevant elements of the means for making electrical contact and automatic physical interlocking of the connector parts is shown at the time when the plug contact fingers 17- are initially be ing inserted into the receptacle slots 40, but beforemaking contact with the female contact portions, It will be ob served in FIG. 6 that a rounded corner 68 is formed on each of the plug contact fingers 17, some of which engage an upper end 64 of a leaf spring 54. Thenormal unstressed condition of leaf springs 46 may also beobservcd in FIG. 6. Further longitudinal movement of the plug toward thereceptacle results in the plug contact fingers 17 being inserted further into the receptacle slots 40, and the receptacle cavities 46. FIG. 7 illustrates sucha representative intermediate position, and it- Will therein be observed that the upper ends 64 of the leaf springs 46, which are free and inherently capable of flexure, have been distorted by the overpowering action of the rounded corners 68 of the plug contact fingers 17, and that the central bowed portions-62 of the leaf springs '46 have also been distorted thereby. Therefore, the leaf springs 46 have been stressed. In FIG. 7 it will be observed that the finger projecting portions 18 have substantially cleared the inner surfaces 53 of the portions of front wall 25 that overlie the cavity portions 48. Prior to reaching the precise FIG. 7 condition, the finger projecting portions 18 werein contact with theedges 7 0 of the front Wall porsnq sh fin r cs asls Slots 0. and we her by imam prevented from lateral movement and the consequential relative rotation of the plug and receptacle. Therefore, the distortion of the leaf springs 54 illustrated in FIG. 7 results, and the leaf springs are stressed. It will also be observed in FIG. 7 that electrical contact between the connector parts has been made, principally by the finger projecting portions 18 and the female contact portions 62. On clearing the edges 70, the finger projecting portions 18 are free to move into the portions 48 of the receptacle cavities 46, and, in fact, are so moved automatically by the unstressing action of the leaf springs 54. The final positions and condition of the plug contact fingers 17, their projecting portions 18 and the cooperating portions of the receptacle are shown in FIG. 8, wherein it will be clearly seen that the leaf springs 46 have returned to their normal unstressed condition, electrical contact is now principally made by the plug contact fingers 17 and the female contact portions 36, and that the plug and receptacle are connected and interlocked by virtue of the finger projecting portions 18 making interference contact with the inner surfaces 53 of the portions of front wall 25 which overlie the receptacle cavity portions 48. It will, therefore, be observed that both electrical contact and physical interlocking of the plug and receptacle are effected simply by moving these parts longitudinally toward each other, and that this single motion automatically results in the relative rotation of the parts to effect interlocking. It will be understood that when finally assembled, as illustrated in FIG. 8, the parts may not he accidentally disconnected by longitudinal separating forces, and that in order to effect separation, it is necessary to intentionally rotate the parts relative to each other and then pull them apart longitudinally.

It will also be understood by those skilled. in the art that while the materials for some of the plug and receptacle elements have been set forth above, all of the elements will be made of appropriate materials, i.e., electrical conducting or insulating materials, and be electrically connected in conventional manners to the electrical leads of the electrical devices, cables and the like, which are wired to them.

FIGS. 9 through 13 illustrate a second modification of the invention, which basically operates on the same principle and in the same manner as the first modification disclosed. Throughout FIGS. 9 through 13, the same reference numerals with a prime added will be used to designate corresponding elements of the two modifications which are substantially the same. New reference numerals will be applied. to those elements which differ in structure significantly from their corresponding elements in the other modification.

The principal diiferences in the modification illustrated in FIGS. 9 through 13 from that of the first modification resides in structural alterations made in the receptacle 12, and these differences reside principally in providing alternative structural means for automatically causing rotation of the plug relative to the receptacle when the connector parts are pushed together, as can best be gleaned by comparing FIGS. 9 and 10 to FIGS. 3 and 5, respectively. It should be noted, for example, that the portions in the second modification of the receptacle cavities 46 have been extended laterally to include additional cavity portions 72. The camming shoes 74 are fiat members which are pivotally mounted on fixed pivot pins 76 that are supported in the receptacle body member 24 and have portions generally vertically disposed in receptacle cavities 46' and in the additional cavity portions 72, as can be clearly seen in FIG. 9. It will also be there observed that the shoes 74 include lower ends '78 that are pivotally secured to pivot pins 76, which are generally horizontally oriented, upper arcuate c-am portions 80, each of which has a vertically extending stop car 82 at its upper end, and horizontally extending pins 84 formed midway and on one side thereof which function to position one end of coiled compression springs 6 '86, the other ends of which make frictional contact with wall portions 88 that partially form the additional cavity portions 72. In order to assist in mounting the compression springs 86, retaining slugs 90 are secured in the additional cavity portions 72 below said springs.

The camming shoes 74 are mounted for oscillation between 21 normal projecting position, shown in FIGS. 9, l1 and 13, and a retracted position, shown in FIG. 12. The shoes 74 are urged to their projecting position by the compression springs 86, and their projecting limit is fixed by the stop lugs 92 which depend from the front wall 25'. The retracted limit of the shoes 74 is fixed by contact of the stop cars 82 with the wall portions 94 which in part define the additional cavity portions 72.

As pointed out above, the shoes 74 are normally disposed in their projecting position. It will be observed in FIGS. 9 and 11 that in such projecting position, an edge portion of each of the cam portions of the shoes contacts the edges of female contact portions 36', and that the shoe stop cars 82 contact stop lugs 92. If it is desired to connect the plug and receptacle, the plug contact fingers 17' are inserted into the arcuate slots 40, as illustrated in FIG. 11. On further insertion, the rounded corners 68' of the plug contact fingers 17 contact the cam portions 80 of the shoes 74. The effect of such con tact is to overcome and distort the compression springs 86 and force the shoes 74 to pivot and retract, thereby stressing the springs 86, as will be seen in FIG. 12. When the projecting portions 18 of the plug fingers 17' clear the edges 70,.they are free to be moved laterally auto matically by the shoes 74, and, in fact, are so moved, as a result of the compression springs 86 unstressing themselves. FIG. 13 illustrates the connector parts after they have been automatically rotated relative to each other by the shoes 74. When the connector parts are finally connected, the projecting portions 1 8 of the plug contact fingers. 17 make interlocking contact with the inner surfaces 53' of the portions of the receptacle front wall 25' 4 0- which overliecavity portions 48.

The operation of the second modification, illustrated in FIGS. 9 to 13, is substantially the same as that of the first modification, and it generally possesses similar advantages. In both cases, electrical connection and physical interlocking of the connector parts are achieved simply by the single motion of moving the connector parts longitudinally toward each other. Herein lies the principal advantage of the instant invention over known prior art interlocking electrical connectors, which require two distinct motions to effect interlocked electrical connection, viz., (l) pushing the connector parts together, and (2) then turning the connector parts relative to each other.

In view of the foregoing it is believed that the construction and operation of both illustrated modifications of the invention are clear.

As will be evident from the foregoing description, certain aspects of our invention are not limited to the par ticular details of construction of the examples illustrated, and we contemplate that various and other modifications and applications will occur to those skilled in the art. It is, therefore, our intention that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of our invention.

What We claim as new and desire to secure by Letters Patent of the United States is:

1. An interlocking electrical connector comprising: a body of electrical insulation material; a plurality of chambers formed in said body; said body having a front wall with a plurality of spaced openings individually leading to said chambers; a plurality of electrical conducting contacts carried by said body including U-shapedl spring clips which are disposed individually in said chambers so as to have their open ends face said openings whereby electrical contact fingers of a second connecting member may be inserted through said openings and into said chambers to enter and be engaged by the legs of said U-shaped spring clips on longitudinal movement of the second connector member toward said connector member; said openings being wider than the width of normal electrical contact fingers whereby electrical contact fingers having lateral interlocking projecting portions that are adapted to be rotated into interlocking position relative to said front wall after they are fully inserted into said chambers may be inserted therethrough; and retractible resilient means other than said U-shaped spring clips disposed in at least one of said chambers and having a portion near adjacent edges of the legs of one U-shaped spring clip in the path of the electrical contact finger that is arranged to enter the chamber in which said one U-shaped spring clip is mounted to engage an edge portion of the electrical contact finger and laterally bias it between the legs of said one U-Shaped spring clip when it is fully inserted into said body, whereby its lateral projecting portion is automatically moved into interlocking position relative to said front wall, and a biasing portion for said portion in contact with a wall of said body which forms the chamber in which said one U-shaped spring clip is mounted which functions to back up the biasing portion; said resilient means comprising a leaf spring that includes a .bowed central portion that is disposed near adjacent edges of the legs of said one U-shaped spring clip, an end rigidly secured to said one U-shaped spring clip and a free end that contacts the wall of. said .body which forms the chamber in which said leaf spring is mounted and functions. as a backing wall for the leaf spring.

2. The device defined in claim 1 wherein said one U- shaped spring clip and said leaf spring are part ofa unitary contact unit that is bodily removably mounted in a chamber in said body.

3. An. interlocking electrical connector comprising: a body of electrical insulation material; a plurality of chambers formed in said body; said body having a front wall with a plurality of spaced openings individually leading to said chambers; a plurality of electrical con-. ducting. contacts. carried. by said. body including U-shaped spring clips which are disposed individually in said chambers so as. to have their open ends face said openings whereby electrical contact fingers. of a second connecting member may. be inserted through said openingsv and into saidcharnbers to enter and be engaged by the legs of said U-shaped spring clips on longitudinal. movement of the secondconnector member toward said connector member; said openings being Wider than the width of normal electrical contact fingers whereby electrical contact fingers having lateral interlocking projecting portions that are adapted to be rotated into interlocking position relative to said front wall after they are fully inserted into said chambers may be inserted therethrough; and retractible resilient means other than said U-shaped spring clips disposed in at least one of said chambers and having a portion near adjacent edges of the legs of one U-shaped spring clip in the path of the electrical contact finger that is arranged to enter the chamber in which said one U-shaped spring clip is mounted to engage an edge portion of the electrical contact finger and laterally bias it between the legs of said one U-shaped spring clip when it is fully inserted into said body, whereby its lateral projecting portion is automatically moved into interlocking position relative to said front wall, and a biasing portion for said portion in contact with a wall of said body which forms the chamber in which said one U-shaped spring clip is mounted which functions to back up the biasing portion; said resilient means comprising a fi-at shoe that is pivotally secured to said body and includes a cam portion that is arranged near adjacent edges of the legs of said one U-shaped spring clip, and a separate spring means for biasing said shoe.

4. The device defined in claim 3 wherein said spring means comprises a spring that at one end is in contact with said shoe and at its other end is in contact with the chamber forming wall, said shoe is normally biased by said spring into a projecting position wherein it is disposed to be contacted by the electrical contact finger on the occurrence of an initial amount of longitudinal movement of the. electrical contact finger into said body and is. retractible laterally against the bias of said spring on further insertion of the electrical contact finger into said body until the projecting portions of the electrical contact fingers clear said front wall at which time said shoe is automatically moved to its projecting position and causes the electrical contact fingers to be moved into alignment with said front wall into interlocking position.

References Cited in the file of this patent UNITED STATES PATENTS 1,678,745 Schellenger July 31, 1928 2,127,544 Von 'Holtz Aug. 23, 1938 2,152,647 Hubbell c Apr. 4,1939 2,188,789 Kimball Jan. 30, 1940 2,643,364 Nauslar June 23, 1953 2,771,590 Nauslar Nov; 20, 1956 FOREIGN PATENTS 77,889 Norway Jan. 8, 1951 

